Torque measuring wrench



March 28, 1939. H. w. ZIMMr-:RMAN

TORQUE MEASURING WRENCH w *Mw 7.. .n T

@722722671112 zzz muy Filed March 6, 1937 Patented Mar. 28, 1939 PATENT. OFFICE TOBQUE MEASURING WRENCH Herman W. Zimmerman,

signor, by mesne assignments, to Fred G. er and Grace J. Wacker, Lake Forest,

Highland Park, Ill., as- Wack- IIL Applloation March 6, 1937, Serial No. 129,357 4 Claims. (Cl. 26S- 1) My invention relates to wrenches, and it has to do particularly with wrenches adapted for measuring the force or torque applied therethrough in' tightening, loosening or otherwise moving nuts,

bolts, studs and other devices.

As is well known, the application of excessive pressure to nuts, bolts, studs, etc., in tightening the same will tend to break or twist on, or otherwise distort, the bolt or stud. The amount of force or pressure that may be applied through a wrench in such cases is determined, in part, by the tensile strength of the bolt or stud material and also somewhat by the depth and pitch of the threads thereof. It is, therefore, desirable that l5 some means be provided for indicating the amount of force or torque applied through the wrench in order that the foregoing objectionable condition may be avoided.

Also, it is quite desirable, in many cases where a plurality of studs or bolts are employed in fastening a device. that all of the studs or bolts be tightened in a uniform manner to insure proper functioning of the device. One example of this is the cylinder head of an automotive engine, in which case it has been found that the lack of uniformity in tightening the cylinder head studs .results in distortion of the head, which lowers the eillciency of the engine.

Still further, it has' been found expedient, in many cases where parts are rotatably fitted together, to determine the nature of the ilt between the parts by measuring the initial force or torqueI A required to relatively rotate such parts. One example of this is the fitting of a bearing. such as a crank shaft bearing. Another example is the fitting of a piston pin, wherein it is desirable to fit the parts in such a way that the resistance to relative movement does not exceed a predetermined extent. An additional example is the fitting of a lathe spindle to its supporting bearings.

It will also be appreciated that, in many cases, the bolts, studs, nuts or other devices to be worked upon are located in places where they are not easily accessible, and a problem is presented in using a wrench, and particularly one embodying provision for the measurement of torque. One of the objects of my invention is to provide an improved wrench device that serves the foregoing purposes and bywhich nuts, bolts, studs and thelike may be readily tightened to a predetermined extent and any number of them may be set up successively in a uniform manner.

Another object is to provide a torque measuring device which is capable, through the provision of suitable adapter devices, for the measuring of the force or torque required to move various rotatably mounted devices, such, for example, as crank shafts, lathe spindles, piston and connecting rod mountings, and the like.

A further object is to provide a torque measuring device of the foregoing character which is quite simple in construction and embodies but very few parts that may be readily and easily assembled and disassembled, is so inexpensive that it may readily nd its way into automotive and other l0 service stations and work shops of practically all classes, is substantially foolproof i`n operation, and is adapted to serve the intended purpose in a highly efficient manner at all times.

Still another object is to provide a torque measl5 uring device that may readily be applied to and used in connection with various forms of ordinary non-torque-measuring wrenches, which device may be used as an accessory to an ordinary wrench.

Further objects and advantages will become apparent as this description progresses, and by reference to the drawing, wherein- Figure 1 is a front elevational view of one form of device embodying my invention;

Fig. 2 is a vertical sectional view of the structure shown in Fig. 1;

Fig. 3 is a top plan view of the structure shown in Figs. 1 and 2;

Fig. 4 is a front elevational view showing 30 another form of device embodying my invention;

Fig. 5 is a vertical section through the structure shown in Fig. 4; and

Fig. 6 is a top in Figs. 4 and 5.

In the drawing, I have shown torque measuring adapter devices that may readily be used as accessories to various well-known forms of wrenches which need not be described in detail herin. 'I'hese devices are comparatively small and may be 40 used in connection with wrenches adapted for work upon nuts, bolts, studs and the like which are disposed in places that are diflcult of access.

The device -Shown in Figs. 1 to 3, inclusive, includes an outer, inverted, cup-shaped shell l0 45 and an inner disk member Il snugly and rotatably tting in the lower open end portion of the shell I0. The disk Il is provided with an axial, squared shank I2 depending from its outer face and adapted to engage any suitable and weliknown means arranged for engagement with a nut, bolt, stud, or other device, which will be referred to at times as "the work". The disk Il is also provided, on its inner face, with a cylindrical, axially-disposed shaft-like plan view of the structure shown 35 projection I 3, lilik 2 the inward end of which is snugly and rotatably supported within a similarly-shaped opening I4 formed in the inner, shell-disposed end of another shank member Il projecting outwardly and axially through the shell top Il.. The outer end Il* of the shank member Il is reduced and squared and it projects outwardly through a similarly-shaped opening formed in the top wall Ill to an extent limited by its enlarged inner end, the arrangement being such that the shell Il and shank member Il rotate together as a unit. The disk projection Il and the shank Il are locked together for relative rotation without axial displacement by a locking ring It engaging complemental, aligned grooves I I* and lib formedv in the projection I3 and socket I4, respectively. With this arrangement, relative rotation between the outer shell Il and the disk II may be accomplished by relative rotation of the shank members I! and Il. The squared portion Il'A of the shank Il is adapted to be engaged by the jaw of an ordinary wrench or any other suitable adapter means that may be employed between this device and the jaw of the wrench. As will become obvious hereinafter, the device may be inverted so that the shank I2, which is preferably sized and shaped similarly to the shank part Ile, may be operatively connected to the wrench jaw while the shank Il is operatively connected to the work.

Relative rotation of the outer shell and disk Il is opposed by a coil torsion spring I1 mounted' within the shell Il and having its upper end connected to the shell Ii and its lower end connected to the disk II. The connections referred to include a clockwise-extending hook portion I1* as viewed in Fig. 3) on the upper end of the spring I1 which engages a pin II carried by and projecting inwardly from the top of the shell Il, and

an oppositely extending hook portion I1 on the other end of the spring which engages a pin I9 projecting upwardly from the inner face of the disk II.

In tightening a nut, bolt, stud, or the like, the shank Il is connected with the wrench jaw and is moved in a clockwise direction as viewed in Fig. 3. With the shank I2 and disk II operatively connected with the work, the clockwise rotation of the shank Ii and shell Il tends to wind up, so to speak, the spring I1 and increase its tension. The sping I1 is of such construction that it has a predetermined initial tension;

or, in other words, it is so constructed that a predetermined force is requiredto overcome its initial tension or at-rest condition before any winding effect or increased tension thereof is accomplished. 'I'he extent of increase in tension of the spring I1 is indicated by the extent of relative rotation of the shell Il and disk II. Certain inch-pounds pressure is required to effect relative rotation of the shell and disk and to increase the tension oi' the spring I1 to any predetermined extent. In the use of this structure to tighten the work, for example, the spring has such an initial tension that the nut, bolt or stud may be set up to a. predetermined point before enough force or torque -is applied through the device to overcome the initial tension of the spring I1; and when the work offers such resistance that the torque applied is greater than the initial tension of the spring I1, the shell III and'disk II rotate relatively, increasing the tension of spring I1 to a point wherein the resistance offered by the work is overcome and the work is `further tightened. This action is continued until the work is tightened to the desired extent, and the extent of relative rotation of the shell Il and disk II indicates the extent 'of increase in tension of the spring l1 and the amount 4of torque applied through the wrench in setting up or tightening the particular work.

In order that the operator may readily determine the amount of force-or torque applied to the work to avoid breakage or to eifect uniformity in tightening the same, I provide an indicating means. This indicating means includes a scale 20 on the lower outer edge of the outer shell III, the scale-bearing surface being beveled to provide a very thin shell edge located in close proximlty to the outer peripheral surface of the disk II, the lower part of which projects below the lower shell edge. The projecting part of the disk II is provided with a zero, or other similar, marker 2l, and the indicator markings of the scale 20 are so located that, when the device is at rest (Figs. 2 and 3) the zero mark of the scale 2l registers with the zero mark 2| on the disk I l. The graduations of the scale 20 preferably indicate inch-pounds pressure. It will, therefore, be seen that, in tightening a nut, bolt, or the like, and when rotation of the shell I0 relative to the disk II takes place in clockwise direction, the position of the scale 20 with respect to the zero mark 2| will indicate the torque condition in inch-pounds pressure. 'Ille operator, knowing the inch-pounds pressure that each particular nut, bolt or the like will stand before breakage, can avoid the latter condition by observing the scale 2l and by discontinuing the application of pressure to the work when the scale 20 indicates that the desired pressure has been reached. Likewise, successive nuts, etc., may be set up to the same desired extent.

The structure shown in Figs. 4 to 6. inclusive, is quite similar to that of Figs. l to 3, inclusive. except that it employs a spiral, clock-type torsion spring 22. Specically, this device includes an outer shell 23 similar to the shell III, except that it is of less depth. It also includes a disk 24 similar to the disk II. The outer shell 24 has an integral, axial, squared extension 25, and the disk 24 has a similar extension 2i, which extensions serve the purposes of the shanks I5 and I2 of the previously-described form. The disk 24 is further provided with an axial shaft-like member 21 extending upwardly from its inner face with its inner end rotatably received in a socket 2l formed in the inner wall of the outer shell 23 on the axis thereof. In this way, like in the first form, the shell and disk are mounted and guided for relative rotation without the tendency of the parts to bind upon each other.

Relative rotation of the shells 23 and 24 is opposed by the spring 22, one end of which is secured to the disk shaft 21 by a screw 29 and the other end is secured to the inner wall of the shell 2l by a screw 30. The spring 22 holds the parts against axial separation.

In the use of the structure shown in Figs. 4 to 6, inclusive, the same practice is carried out as in connection with the form already described. The spring 22 opposes relative rotation between the 4shell 23 and disk 24 and its initial tension is overcome only when the work (nut, bolt or the like) offers suillcient resistance. The extent of relative rotation between these parts, as measured in inch-pounds pressure, is indicated by the scale 3| on the outer surface of the shell 23 and the zero marker 32 on the disk 24.

I `believe that the operation of my invention,

as well as the advantages hereinabove stated, will be understood from the foregoing description. connecting element non-rotatably associated with The structures shown and described may well th closed end of said shell member, both said or a crank shaft, or piston and connecting rod sure applied to effect relative rotation between 10 mountings. In other words, in the use of my said shell and disk members in opposition to said invention, the fit of devices oi' this character may spring. be readily determined and accurately adjusted. 3. 'In structure of the class described, an an- It is to be understood that while I have shown `nular shell member having an open end and a two iorms oi' devices embodying my invention, closed end; a comparatively shallow disk mem- 15 other changes in details and arrangements of ber rotatably mounted in the open end oi said I cl means between said shell and disk members, a 2o the work, means on the other oi' said members by said members, similar means on both said mem- Which I'Otatiimal mOVement may be applied therebers for engaging the same either with the work. 25 t0. bOth Said means being so constructed and or wi an object adapted to apply rotational. arranged that either of said members may be movexlent thereto, and registering scale means connected with the work with the other member on thl open end edge portion of said shell and adapted to have rotational movement applied on the outer projecting part oi' said disk memthereto, permitting the structure as a whole to be ber.

used in an upright or an inverted condition, a tor- 4. In structure of the class described, an ansion spring between said members and having one nular shell member having an open end and a end positively connected to one of said members closed end, a comparatively shallow disk mem- 0f Said members S0 that Said Spring yieldingly opshell member with a part of'its periphery pro- 35 relative rotation thereof as opposed by said tion between said members, an exterior element o Spring. extending axially from the closed end of said shell 2. In structure of the class described, an anmember, an exterior element extending axially nular shell member having an open end and a from said disk member, both-said elements clem end, a comparatively shallow disk member constructed and arranged for connection with the rotatably mounted in the open end oi' said shell work or with an object for applying rotational member with a part o! its periphery projecting movement thereto, rotatably engaged guide lsaid shell member and at its other end to said means on the exposed part of said disk member disk member, an outwardly projecting axial conand on the exterior open end portion oi' said shell o necting element non-rotatably associated with member.

said disk member. an outwardly projecting axial HERMAN W. ZIMMERMAN. 

